Question

Give the general characteristics of alkali metals and alkaline earth metals with reference to reactivity.

Answer 1

General characteristics of alkali metals and alkaline earth metals with reference to reactivity:

Based on its reactivity we can list some of the general characteristics of Alkali and alkaline earth metals.

(i) Reaction with water

We can see that the reactivity of alkali metals with water is more violent as it occupies a higher position in the reactivity series and they can displace hydrogen more easily from water than the alkaline earth metals.

For example,

$2\mathrm{K}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{KOH}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\uparrow$

(ii) Solubility of hydroxides
Alkaline earth metals have more lattice energies than alkali metals due to their small size and high charge. Thus, alkaline earth metal hydroxides show lower solubility than alkali metals.

(iii) Polarising power of cations
The alkali metal ions have the lowest polarising power as their charge/radius ratio is very low, whereas the alkaline earth metal ions have high polarising power as it forms bivalent ions and the charge/radius ratio is higher than the alkali metals. Based on its reactivity we can list some of the general characteristics of Alkali and alkaline earth metals.